Device on elevators for stopping exactly at floor level



April 1, 1958 a. slPlEss ETAL DEVICE ON ELEVATORS FOR STOPPING EXACTLYAT FLOOR LEVEL Filed Aug. 9, 1955 2 Sheets-Sheet 1 INVENTORS uswvv SPK44 81-0 2,828,832 DEVICE ON ELEVATORS FOR STOPPING EXACTLY AT FLOOR-LEVEL Filed Aug. 9, 1955 April 1, 1 958 G. SPIESS EI'AL 2 Sheets-Sheet 2DEVICE N ELEVATORS FOR STOPPING EXACTLY AT FLOOR LEVEL Gustav Spiess andKarl Stutz, Lucerne, Switzerland, assignors to lnventioAktiengesellschaft, Hergiswil, Switzerland, a Swiss firm ApplicationAugust 9, 1955, Serial No. 527,331 Claims priority, applicationSwitzerland August 12, 1954 6 Claims. (Cl. 187-29) With devices onelevators for stopping exactly at floor level, it has hitherto beennecessary for accuracy of stopping to approach the fioor level with alonger or shorter period of slow running, depending on the loading ofthe elevator.

The purpose of the present invention is to create a device for the exactstopping at floor level, which will allow of bringing the elevator underany load direct to floor level without any slow running.

According to the invention, this result is obtained by a device whichhas a rotor rotatable in a magnetic field, and also a tachometer dynamo,the two being coupled to the hoisting motor, further means, arrangedpartly on the elevator cage and partly on the different floors, forregulating the voltage of a source of voltage in dependence on thebraking path, and an amplifier for supplying exciting current for themagnetic field, with a control grid which is connected to the differencebetween the voltages of the tachometer dynamo and of the voltage source,these two voltages being arranged to oppose each other.

The above, and other objects, features and advantages of the invention,will be apparent in the following detailed description of illustrativeembodiments thereof which is to be read in connection with theaccompanying drawings forming a part hereof, and wherein:

' Fig. 1 is a diagrammatic view of a device embodying the presentinvention;

Fig. la is a wiring diagram of a push button control means associatedwith the device of Fig. 1;

Fig. 2 is a diagrammatic view of an assembly that can be substituted inthe device of Fig. 1 in accordance with another embodiment of theinvention, 7

Fig. 3 is a diagrammatic view of an assembly that can be substituted inthe device of Fig. 1 in accordance with another embodiment of theinvention; and

Fig. 4 is a diagrammatic view of an assembly that can be substituted inthe device of Fig. 1 in accordance with still another embodiment of theinvention.

In the embodiment according to Fig. l, a main motor HM is provided fordriving the winch (not illustrated) for the elevator cage or car and canbe connected to a three-phase supply system through two switches S and SThe motor HM is coupled to a tachometer dynamo T, an eddy-current brakeWB, and a brake drum B of a. magnetic brake. The brake shoes BB of thebrake are pressed against the brake drum B by means of springs and maybe. released by means of a magnet BM, which is connected through aswitch S to a D. C. supply system. I

At the separate floors, control cams C are arranged, one for the upwardtravel and one for the downward travel. A roller R, fitted on a leverarm H, is urged, by means of a spring F, against one of the cams C insuch a way that the lever arm is swung in one direction. The lever arm His connected to the-rotatable Patent part of an induction regulator I,the primary part of which is connected to a three-phase supply systemthrough a switch S The secondary voltage of the induction regulator J isconnected to a rectifier GR, from which a direct current voltageproportional to the secondary voltage is taken and led to terminals K.

Through switch S or S (depending on the direction of travel), thevoltage of the tachometer dynamo T is opposed to the voltage at theterminals K and the resultant voltage applied to the control grid of anamplifying tube V.

The anode current of the amplifying tube V controls a rectifier TH withthyratron tubes, for feeding the exciter winding of the eddy-currentbrake WB with a current i. The rectifier TH is connected to an A. C.supply system by means of a switch S The anode of the tube V and thethyratron rectifier are further connected through resistances W to theterminals of a D. C. supply in a conventional manner.

The wiring for controlling the device of Fig. 1 is illustrated in Fig.la.

In order to provide automatic pushbutton control for an elevatorservicing four floors, there are provided, in the cage, the pushbuttonsDC and, at the several floors, the calling pushbuttons DR Contacts KSactuated by the elevator shaft doors prevent operation of the elevatorwhen a door is open.

The landing relays re each have a self-holding contact 1re and a workingcontact 2re The switches S1-S7 are solenoid actuated and are shown inFig. la with their magnet coils actuating the main contacts shown inFig. 1. Some of these switches are provided with auxiliary contacts.Specifically, switch 8 has a self-holding contact 15 and an open circuitcontact 25 switch S has a self-holding contact 18 and an open circuitcontact 28 switch S, has two closed circuit contacts 18 and 48 and twoopen circuit contacts 25 and 35 switch S has two closed circuit contacts18 and 45 and two open circuit contacts 23 and 35 and switch S has aclosed circuit contact 18 and an open circuit contact 25 The copyinggear has, for each floor, a contact CA which is set in a medium positionas soon as the roller R has reached the point a on the related cams C. Acommon contact CF on the copying gear is opened only when the bottom ofthe cage is exactly aligned with a I tacts tra and 2re so that Theoperation of the described device is as follows:

' Assuming the cage to be disposed at the first floor, pushing thecalling pushbutton DR on the third floor causes the landing relay re tobe excited by a circuit extending from the negative terminal, throughclosed circuit contact 18 calling pushbutton DR;, and landing relay reto the positive terminal. I

The landing relay re is actuated and closes its conthe switch S isexcited by a circuit extending from the. negative terminal, throughcontact 2re copying gear contact CA closed circuit contact 18,, and thecoil of the switch S to the positive terminal.

The switch S is actuated and connects the main motor HM, opens theclosed circuit contacts 18 and 45 and closes the open circuit contacts28 and 3S The landing relay re holds itself through contact 28 andself-holding contact 1re so that the calling pushbutton may be releasedagain, while contact 38,, connects switch S by a circuit extending fromthe negative terminal, through contact 38 and the coil of the switch Sto the positive terminal. Switch 8;; is actuated, connects thetachometer dynamo T, and closes the contacts 18 (as a preparation forself-holding) and the open circuit contact 2S3.

aeaaesa Through contact 25 switch S is actuated by a circuit extendingfrom the negative terminal, through contact 28 and the coil of switch Sto the positive terminal.

Switch S is actuated and connects the brake release magnet BM, opens theclosed circuit contact 18 and closes the open circuit contact 28 whichfor the moment, has no effect, since contact 48 is already opened. Nowthe cage travels upwards, while the roller R, under the influence of thespring F follows the upper cam C, or alternatively may be spaced fromthe cam in a manner not shown. When the cage is spaced by a distance 3from the third floor, the contact 3CA opens.

Therefore, switch S is released and the main motor HM. is disconnected.

Closed circuit contacts 18 and 43 close, and open circuit contacts 28and 38 open.

The landing relay re releases, as its self-holding is interrupted bycontact 23 Switch 83 remains excited, as it is held through copying gearcontact CF and contact 18 Therefore, switch S7 also remains excited andthe brake BB continues in its released condition. Simultaneously, theswitches S and S are excited by a circuit extending from the negativeterminal, through contacts 48 48 25 and switches S and S to the positiveterminal.

Switch S connects the induction regulator J, and switch S connects the,thyratron rectifier TH, with the A. C. supply system.

The rectified secondary voltage of the induction regulator J on theterminals K in this moment has a value which is equal to the voltage ofthe tachometer dynamo T. The tube V is fully opened and the thyratronrectifier TH is interrupted, so that the eddy-current brake is notexcited.

As the travel of the cage continues the roller R follows the cam C and,in view of the deflection of the lever arm H, the secondary voltage ofthe induction regulator J, and thus the voltage at the terminals Kbecomes lower than the tachometer voltage.

The voltage of the control grid of the tube V becomes negative, theanode current increases and opens the thyratron rectifier TH. Theeddy-current brake WE is now excited, so that the cage is retarded. Thebraking operation is controlled in such a way, that the voltage of thetachometer dynamo T decreases in accordance to the voltage at theterminals K.

When the bottom of the cage is exactly at the same level as the floor,the voltage at the terminals K is zero, and, therefore, also the voltageofthe tachometer dynamo T has to be zero, the cage being at rest.

At the same time the contact CF 0n the copying gear is opened, so thatswitch S is released, the tachometer dynamo T disconnected and auxiliarycontact 25 releases switch S The braking magnet is thereby released, sothat the mechanical brake BB becomes effective.

The contact 25 disconnects the switches S and S the induction regulatorJ and the thyratron rectifier TH are disconnected from their currentsupplies.

Another landing relay may then be excited for starting a new travel bymeans of the pushbuttons DC or DR through the contact 18 which is closedagain.

The voltage, lowering when approaching a floor and opposed to thevoltage of the tachometer dynamo, could also, as illustrated in Fig. 2,be taken from a transformer P, S with loose-coupled magnetic circuit,where a coupling piece M, which can be drawn out the magnetic circuit,reduces the coupling and thereby the secondary voltage of thetransformer. The coupling piece M is shaped as a flat strip, running toa point at both ends, whereby these ends cause a gradual reduction ofthe coupling and consequently also of the secondary. voltage.

As illustrated in Fig. l, theterminals K are connected tothe tachometerdynamo T and to the grid of thetube According to Fig. 3, abridge-connection of four capacitors C C C and C; can be provided,whereby the capacitor C has a movable coupling piece N for graduallyaltering the capacitance of the capacitor C Such a coupling piece N,running to a point at each end, is arranged on each floor and, when theelevator is approaching that floor, runs in between the coatings of thecapacitor fitted in the cage of the elevator.

To one diagonal of the bridge-connection an alternating-current sourceis connected, whilst from the other diagonal a variable voltage can betaken, led to a rectifier GR, and taken as direct-current voltage at theterminals K.

For supplying the variable voltage to the terminals K, a potentiometer Wmay also be provided, as shown in Fig. 4. This is connected to adirect-current source and the variable, gradually reducing voltage istaken off by a sliding contact.

Having now particularly described and ascertained the nature of our,said invention and in what manner the same is to be performed, wedeclare that what we claim is:

1. In a device for' controlling the travel of an elevator cage servicinga plurality of floors; the combination of braking means having a rotorrotatable in a magnetic field, a tachometerdynamo and a hoisting motorall coupled together, control means actuable at each of the floors andfrom within the elevator. cage for controlling the operation of saidhoisting motor so that the elevator cage may be made totravel from floorto floor, as desired, a source of voltage, regulating means arrangedpartly on the elevator cage and partly at the different floors to beserviced and operative to regulate the voltage from said source as afunction of the position of the elevator cage in relation to the floorto which the cage is being made to travel by said. control means, anamplifier for supplying exciting currentv to said magnetic field of thebraking means, said amplifier having a control grid, and meansconnecting. said control grid to said tachometer dynamo and to saidregulating means with the voltage from said tachometer dynamo and theregulated voltage from. said source opposing each other so that theeffect of said braking means is varied in dependence on the position ofthe elevator cage relative to the floor to which the latter istravelling.

2. In a device for controlling the travel of an elevator cage servicinga plurality of floors; the combination as in claim 1, wherein saidregulating means includes control cams, arranged at each of the floorsto be serviced, a cam follower lever mounted on the elevator cage andengageable. with'said'carns at each floor to be deflected by said camsto an extent dependent upon the position of the cage relative to thefloors, and an induction regulator having a primary connected to saidsource of voltage and a secondary connected so that the voltage at thelat-. ter opposes the voltage of said tachometer dynamo, said inductionregulator being controlled by said cam follower lever so that thevoltage at said secondary is gradually reduced in responset'o defiectionof said lever by said cams as the elevator cage approaches a floor atwhich the cage is to be stopped.

3. In a device for controlling the travel of an elevator cage servicinga plurality of floors; the combination as in claim 1, wherein saidregulating means includes a transformer at each of the floors having itsprimary connected to said, source of voltage and its secondary connectedso that the. voltage thereof opposes the voltage of said tachometerdynamo, and an adjustable coupling piece movable in the magnetic circuitof said transformer in response to movement of the elevator cage togradually .re-, duce, the secondary voltage of the transformerassociated with the. floor at which the cage is to be stopped as thecage approaches said floor.

4 Inv a device for controlling the travel of an elevator cage servicinga plurality of floors; the combination as in claim 1, wherein saidregulating means includes a variable capacitor connected to said source,and a coupling piece movable in response to travel of the elevator cageto cause said capacitor to gradually reduce the voltage of said sourceas the elevator cage approaches a floor at which the latter is to bestopped.

5. In a device for controlling the travel of an elevator cage servicinga plurality of floors; the combination as in claim 1, wherein saidregulating means further includes three additional capacitors connectedwith said variable capacitor to form a bridge-connection.

6. In a device for controlling the travel of an elevator cage servicinga plurality of floors; the combination as in claim 1, wherein saidregulating means includes a potentiometer on the elevator cage connectedelectrically to said source to vary the voltage from the latter, and asliding contact at each of the floors engageable with said potentiometerto gradually reduce the voltage from the latter as the cage approaches afloor at which it is to be stopped.

No references cited.

